git: b01f66cb0e3b - stable/15 - proc: free kstack buffers when debug permission changes

The branch stable/15 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=b01f66cb0e3bdf7f12bac161feaf9bc4d3a5a091

commit b01f66cb0e3bdf7f12bac161feaf9bc4d3a5a091
Author:     Andrew Griffiths <andrew@calif.io>
AuthorDate: 2026-09-14 07:55:01 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-09-28 13:38:01 +0000

    proc: free kstack buffers when debug permission changes
    
    The kern.proc.kstack handler allocates its output and stack buffers
    before deliberately checking p_candebug again under the process lock.
    If trace-control state changes between authorization checks, the failure
    path balances the process and exec state but leaks both buffers.
    
    Submitted by calif.io for the OpenAI Patch The Planet program
    
    Signed-off-by: Andrew Griffiths <andrew@calif.io>
    
    Fixes:          8b5abd9027b8 ("kern_proc.c: disallow execve around sysctl kern.proc.kstacks")
    Reviewed by:    markj
    MFC after:      1 week
    
    (cherry picked from commit 3484217cc47c1f77d2be2ed0e012b870d1cd3dca)
---
 sys/kern/kern_proc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index add8cbcde1d5..90b558adaf46 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -2892,6 +2892,8 @@ sysctl_kern_proc_kstack(SYSCTL_HANDLER_ARGS)
 		execve_unblock(ctd, p);
 		_PRELE(p);
 		PROC_UNLOCK(p);
+		stack_destroy(st);
+		free(kkstp, M_TEMP);
 		return (error);
 	}
 	do {